Europe's solar industry saw mixed irradiance patterns in September, as widespread high-pressure conditions delivered above-average irradiance across much of the continent, even as severe floods and storms disrupted solar potential in key regions like France, Italy and the UK. This variability is expected to continue, with a clear north-south split in conditions forecast for the remainder of autumn, according to analysis using the Solcast API.
September was dominated by a persistent high-pressure system centered over Eastern Europe. This atmospheric blocking pattern suppressed cloud formation and created ideal conditions for solar irradiance across a broad swathe of the continent. Many regions
recorded irradiance levels more than 10% above the long-term average. Notably, Finland experienced its third warmest September on record, and from September 19th to 22nd, a heat dome intensified temperatures by up to 15 C in just 48 hours across Central and
Eastern European regions. These conditions enabled solar assets across these regions to benefit from exceptional late-summer irradiance.
However, the same high-pressure system contributed to unstable weather on its western flank. Low pressure over the UK drew in moist Atlantic air, increasing cloud cover and rainfall in France and parts of Eastern Germany, where irradiance fell roughly 15% below normal. High Mediterranean sea surface temperatures further increased atmospheric instability, coupled with a southward-displaced jet stream to enhance thunderstorm development. This led to flash flooding in several regions of France and Italy, with parts of northern Italy recording up to 100 mm of rainfall within 24 hours. These conditions severely limit solar output in affected areas.
October began with more extreme weather. Storm Amy brought record-breaking winds to the UK and Ireland, with gusts exceeding 100 mph and causing widespread power outages. The storm system also delivered extensive cloud and rainfall, compounding already poor
irradiance levels in northwestern Europe.
Looking ahead, forecasts point to a significant meteorological divide. Northern Europe, particularly the Northern UK and Southern Norway, is expected to see up to 25% more rainfall and 10% more cloud cover than average, leading to a 5% reduction in solar irradiance in some regions. In contrast, Southern Europe is likely to benefit from continued high-pressure dominance. Spain and Italy are forecast to experience a reduction in cloud cover of up to 10% and 25% less rainfall, supporting stronger solar conditions into late autumn.
Solcast produces these figures by tracking clouds and aerosols at 1-2km resolution globally, using satellite data and proprietary AI/ML algorithms. This data is used to drive irradiance models, enabling Solcast to calculate irradiance at high resolution, with typical bias of less than 2%, and also cloud-tracking forecasts. This data is used by more than 350 companies managing over 300 GW of solar assets globally.
The views and opinions expressed in this article are the author’s own, and do not necessarily reflect those held by pv magazine.
This content is protected by copyright and may not be reused. If you want to cooperate with us and would like to reuse some of our content, please contact: editors@pv-magazine.com.
By submitting this form you agree to pv magazine using your data for the purposes of publishing your comment.
Your personal data will only be disclosed or otherwise transmitted to third parties for the purposes of spam filtering or if this is necessary for technical maintenance of the website. Any other transfer to third parties will not take place unless this is justified on the basis of applicable data protection regulations or if pv magazine is legally obliged to do so.
You may revoke this consent at any time with effect for the future, in which case your personal data will be deleted immediately. Otherwise, your data will be deleted if pv magazine has processed your request or the purpose of data storage is fulfilled.
Further information on data privacy can be found in our Data Protection Policy.